Embryology and Development Practice Questions

Q: The diagram given below depicts the various parts from which the diaphragm develops. Defect in which part most commonly leads to congenital diaphragmatic hernia? (AIIMS May 2016)

A. ***A*** - A indicates the **pleuroperitoneal membranes**, which are posterior and lateral structures that form a significant portion of the diaphragm. - Failure of these membranes to fuse with other diaphragmatic components, particularly on the left side, leads to a **Bochdalek hernia**, the most common type of congenital diaphragmatic hernia. *B* - B represents the **septum transversum**, which forms the central tendon of the diaphragm and contributes to the anterior portion. - Defects in the septum transversum can lead to **Morgagni hernias**, which are less common than Bochdalek hernias and are typically anterior and retrosternal. *C* - C indicates the **mesentery of the esophagus**, which forms the crura of the diaphragm. - Defects in this region are rare causes of diaphragmatic hernia and usually involve the posterior medial aspect. *D* - D points to the **muscular ingrowth from the body wall**, which forms the peripheral musculature of the diaphragm. - While essential for complete diaphragm formation, isolated defects in this part are less commonly implicated as the primary cause of major congenital diaphragmatic hernias compared to the pleuroperitoneal membranes.

Q: Portal vein develops from which of these structures? (AIIMS May 2016)

B. ***B*** - In this diagram illustrating embryonic vein development, the structure labeled **B** represents the **right vitelline vein**, which contributes significantly to the formation of the portal vein system. - The **portal vein** is formed from the anastomosing network of the vitelline veins around the duodenum, with the right vitelline vein becoming its main stem. *A* - The structure labeled **A** represents the **anterior cardinal veins**, which contribute to structures like the superior vena cava, not the portal vein. - These veins drain the cranial part of the embryo. *C* - The structure labeled **C** represents the **left vitelline vein** which, in later development, largely **regresses** or contributes to smaller veins, unlike the right vitelline vein shown at B. - While part of the vitelline system, its contribution to the definitive portal vein is minor compared to the right vitelline vein. *D* - The structure labeled **D** represents the **umbilical veins**, which carry oxygenated blood and nutrients from the placenta to the fetus. - Postnatally, the umbilical veins obliterate to form the **ligamentum teres hepatis** and the **ligamentum venosum**, and do not form the portal vein.

Q: Which of the following marked structures would give rise to the heart?

D. ***D*** - Structure **D** indicates the region where the **cardiac prominence** or **heart bulge** is forming in this early embryo. - The heart is one of the earliest organs to develop and begin functioning during embryogenesis, appearing as a prominent bulge in the ventral region. *A* - Structure **A** points to the **cephalic region** or **head fold** of the embryo, which will develop into the brain and associated structures. - This region is primarily involved in the formation of the **nervous system** and sensory organs. *B* - Structure **B** indicates the **somites**, which are segmented blocks of mesoderm that form along the neural tube. - Somites give rise to the **vertebrae, ribs, skeletal muscles** of the trunk, and dermis of the skin, not the heart. *C* - Structure **C** points to the **developing brain** or neural tube in the head region of the embryo. - This structure is critical for the formation of the **central nervous system**.

Q: A young patient with absent thymus presents with tetany and hypoparathyroidism. Which of the following is a marked area in the picture defective in this condition?

C. ***C*** - The image shows the **pharyngeal arches and pouches** during embryonic development. **C** points to the **third pharyngeal pouch**, which gives rise to the **thymus** and inferior parathyroid glands. - A defect in the development of the third pharyngeal pouch would lead to an **absent or hypoplastic thymus** and **hypoparathyroidism**, causing symptoms like tetany due to hypocalcemia. This condition is known as **DiGeorge syndrome**. *A* - **A** points to the first pharyngeal pouch, which develops into the **auditory tube** and **tympanic cavity**. - Defects in the first pharyngeal pouch would primarily affect structures in the ear, not the thymus or parathyroid glands. *B* - **B** points to the fourth pharyngeal pouch, which gives rise to the **superior parathyroid glands** and the **ultimobranchial body** (parafollicular C cells of the thyroid). - While hypoparathyroidism could be involved, the primary defect in DiGeorge syndrome affects the third pouch, leading to both thymic and parathyroid issues more comprehensively. *D* - **D** points to the first pharyngeal arch, which contributes to the formation of the **mandible**, **maxilla**, and several muscles of mastication. - Defects in the first pharyngeal arch are associated with conditions like **Treacher Collins syndrome** or **Pierre Robin sequence**, which present with facial dysmorphism rather than thymic or parathyroid agenesis.

Q: Nucleus pulposus develops from: (AIIMS May 2018)

C. ***Correct Option C*** - Label C points to the **notochord**, which is the embryonic structure that the **nucleus pulposus** of the intervertebral discs develops from. - The notochord provides transient axial support during early embryonic development and induces the formation of the neural tube. - During development, most of the notochord degenerates, but remnants persist as the gelatinous core of intervertebral discs. *Incorrect Option A* - Label A indicates the **neural tube**, which develops into the **brain and spinal cord**. - It arises from the neural plate, which is induced by the underlying notochord. - The neural tube does not contribute to the intervertebral disc structure. *Incorrect Option B* - Label B represents the **secondary yolk sac**, a structure involved in early nutrient transfer and the formation of primordial germ cells. - It does not directly contribute to the formation of musculoskeletal structures like the nucleus pulposus. *Incorrect Option D* - Label D points to the **ectoderm**, the outermost germ layer, which gives rise to the epidermis, nervous system (including the neural tube), and sensory organs. - While it forms the neural tube, it does not directly form the nucleus pulposus or other mesodermal derivatives.

Q: For the formation of the shown monozygotic twins, division should take place by

>14 days. ***>14 days*** - The image shows **conjoined twins**, which results from an incomplete separation of a single zygote. - This very late and incomplete division occurs when the zygote splits after **more than 14 days** post-fertilization, after the formation of the embryonic disc. *<3 days* - Division within the first three days results in **dichorionic-diamniotic twins**, meaning each twin has its own chorion and amnion. - This scenario would show **two separate placentas** and two distinct amniotic sacs. *4-8 days* - Division between 4 and 8 days typically leads to **monochorionic-diamniotic twins**, where twins share a placenta but have separate amniotic sacs. - The image depicts a shared sac and an incomplete division of the embryo itself. *8-14 days* - Division between 8 and 14 days results in **monochorionic-monoamniotic twins**, where twins share both a placenta and an amniotic sac. - While sharing a sac, this period usually leads to two distinct, non-conjoined fetuses within that single sac.

Q: Which neural tube defect is shown here:

Anencephaly. ***Anencephaly*** - This image depicts a fetus with anencephaly, characterized by the **absence of a major portion of the brain, skull, and scalp**. - The distinctive features are the **exposed brain tissue** (represented by the light blue and white mass on the head) and the **lack of a developed skullcap** above the eyes. - **Neural tube defect** resulting from failure of the **rostral (anterior) neuropore to close** during weeks 3-4 of embryonic development. - Incompatible with life; most infants are stillborn or die shortly after birth. *Schizencephaly* - **NOT a neural tube defect** - this is a rare **neuronal migration disorder** characterized by abnormal clefts in the cerebral hemispheres. - Results from abnormal neuronal migration during brain development, not from neural tube closure failure. - Does not present with external cranial defects or absence of skull and brain tissue as seen in anencephaly. *Lissencephaly* - **NOT a neural tube defect** - this is a **neuronal migration disorder** characterized by absent or decreased gyri and sulci, giving a smooth brain appearance. - Results from defective neuronal migration during cortical development. - This is an internal structural defect without the obvious external cranial and brain tissue absence characteristic of anencephaly. *Cranioschisis* - Cranioschisis refers to a defect where the **cranium fails to close properly**. - While related to neural tube defects, the image specifically shows **complete absence of the forebrain and skull above the orbits** (anencephaly) rather than simply a skull closure defect with intact but exposed brain tissue.

Q: Name the neural tube defect shown here:

Cranioschisis. ***Cranioschisis*** - *Cranioschisis* refers to a **fissure or defect in the skull**, often associated with exposure of brain tissue. The image shows significant disruption of the cranial vault and exposed tissue, consistent with this condition. - This is a broad term that encompasses various degrees of skull non-closure, typically occurring in the **earlier stages of neural tube development**. *Anencephaly* - *Anencephaly* specifically involves the **absence of a major portion of the brain, skull, and scalp**, resulting from failed closure of the anterior neural tube. While there is a cranial defect, the image appears to show some disorganized brain tissue, not a complete absence. - The characteristic presentation of anencephaly is a **frog-like appearance** due to the exposed brain and absent vault, which is not fully depicted as such here. *Meningocele* - A *meningocele* is a neural tube defect where the **meninges protrude through a defect in the skull or spine**, forming a sac filled only with cerebrospinal fluid. There are no neural elements in the sac. - The image shows exposed neural tissue rather than a fluid-filled sac, making meningocele an unlikely diagnosis. *Iniencephaly* - *Iniencephaly* is a rare and severe neural tube defect characterized by **extreme retroflexion of the head**, a short neck, and often extensive spina bifida. - The image does not clearly demonstrate the characteristic retroflexion of the head or the severe neck anomalies associated with iniencephaly.

Q: The image shows:

Malformation of vitello-intestinal duct. ***Malformation of vitello-intestinal duct*** - The image depicts a **persistent vitelline (omphalomesenteric) duct** remnant, which can present as a patent duct, fistula, cyst, or fibrous band. The appearance here is consistent with an **umbilical polyp or remnant,** presenting as a red, moist lesion often mistaken for granuloma. - This malformation occurs when the **vitello-intestinal duct**, connecting the developing gut to the yolk sac, fails to involute completely. *Omphalocele* - An **omphalocele** involves herniation of abdominal contents (covered by a membrane) through the **umbilical ring**, while this image shows a solid, polyp-like structure. - The umbilical cord is typically attached to the apex of the sac in omphalocele, which is not what is seen here. *Gastroschisis* - **Gastroschisis** is characterized by uncovered abdominal organs protruding through an abdominal wall defect, usually to the **right of the umbilical cord**. - There is no protective membrane in gastroschisis, and the image shows a covered, distinct growth at the umbilicus, not an open abdominal defect with exposed viscera. *Necrotising enterocolitis* - **Necrotizing enterocolitis (NEC)** is an inflammatory condition of the neonatal intestine, leading to **ischemic necrosis**. - This image shows an external umbilical anomaly; internal intestinal pathology like NEC would present with abdominal distension, feeding intolerance, and bloody stools, not this umbilical lesion.

Question 1

As shown in the figure, abnormal subclavian artery develops as a result of: (AIIMS May 2016)

Accepted Answer

Obliteration of B with persistence of A

Answer

Persistence of B

Answer

Persistence of A

Answer

Obliteration of A with persistence of B

Question 2

The diagram given below depicts the various parts from which the diaphragm develops. Defect in which part most commonly leads to congenital diaphragmatic hernia? (AIIMS May 2016)

Accepted Answer

A

Answer

B

Answer

C

Answer

D

Question 3

Portal vein develops from which of these structures? (AIIMS May 2016)

Accepted Answer

B

Answer

A

Answer

C

Answer

D

Question 4

Which of the following marked structures would give rise to the heart?

Accepted Answer

D

Answer

A

Answer

B

Answer

C

Question 5

A young patient with absent thymus presents with tetany and hypoparathyroidism. Which of the following is a marked area in the picture defective in this condition?

Accepted Answer

C

Answer

B

Answer

D

Answer

A

Question 6

Nucleus pulposus develops from: (AIIMS May 2018)

Accepted Answer

C

Answer

A

Answer

B

Answer

D

Question 7

For the formation of the shown monozygotic twins, division should take place by

Accepted Answer

>14 days

Answer

<3 days

Answer

4-8 days

Answer

8-14 days

Question 8

Which neural tube defect is shown here:

Accepted Answer

Anencephaly

Answer

Schizencephaly

Answer

Lissencephaly

Answer

Cranioschisis

Question 9

Name the neural tube defect shown here:

Accepted Answer

Cranioschisis

Answer

Anencephaly

Answer

Meningocele

Answer

Iniencephaly

Question 10

The image shows:

Accepted Answer

Malformation of vitello-intestinal duct

Answer

Omphalocele

Answer

Gastroschisis

Answer

Necrotising enterocolitis

Embryology and Development — MCQs

Embryology and Development — MCQs

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